Preformed metal roofing panel systems provide the benefit of durability and long service life with a minimum of maintenance compared with other types of roofing systems. A typical roofing system includes preformed sheet metal panels with overlapping portions which may or may not interlock.
Each panel includes spaced longitudinal projections extending the length of the panel that provide structural rigidity and also allow mating between panels. The panels are installed on a roof such that the projections extend in the direction of the slope of the roof. The projections create gaps between the panels and any flat underlying support material or base surface on which the panels are installed. These gaps can be filled with closure strips that have a profile complementary to the bottom of the roof panel. The strips are made from a resilient watertight material at the bottom edge of the roof panels. The closure strips' installation prevents wind-driven rain, debris, or insects from entering through the gaps at the bottom edge of the roof and damaging the underlying support structure.
In order to work effectively, the closure strips must be precisely formed with complementary projections that align with the mating panel to close the gaps and prevent foreign matter from passing through to the underlying support material. A perfectly sealed roof, however, is not practicable, and inevitably, moisture finds its way between the roof panels and the underlying materials. Often, humid, warm air is trapped between roof panels and the underlying material during the day time. When the roof cools at night, moisture in the air condenses and is then trapped inside the roof structure by the closure strips. This trapped moisture may cause deterioration of the roof panels and the underlying material. Current roofing systems do not provide ventilation that assists in evaporating this unwanted water. Additionally, the known closure strips have a life of about three years before the material breaks down.
Similar problems are known in tile roofing systems, in which rounded tiles created gaps with similar problems as those discussed above.
Thus, a need exists for a panel roofing system that allows adequate ventilation between the roof panels and the underlying material to prevent deterioration of the roof panels and support material.